QUESTION BANK

RUCHITA GUPTA

MECHANICAL MEASUREMENT & CONTROL

ME IV SEM

UNIT-I

1(a) With the help of suitable block diagram, Discuss the basic functional elements

of a generalized instrumentation system.

(b) Explain clearly through suitable examples the following-

(i) Specification

(ii) Calibration

(iii) Dynamic Response

2. Differentiate between-

(a) Reproducibility & Drift

(b) Dead Zone & Hysteresis

3. Draw neat sketches showing position of electric resistance strain gauges, the

bridge connection for max. output & full temperature compensation.

(a) What are the gauge factor & circuit Sensitivity?

(b) Write the short note on load cells & their calibration.

4. A strain gauge having a resistant 100Ω & gauge factor of 2 is connected in

services with a ballast resistance of 100 Ω across a supply of 12v. Calculate the

difference between the output voltage with no stress applied & a stress of

140µN/m2

. The modulus of elastic is 200GN/m2 .

5. What is use of dummy gauge? Explain that how they effect the output of a

strain gauge bridge.

6. A strain gauge has a resistance of 120Ω unstrained & the gauge factor is -12.

What is the resistance value if the strain is 1%.

UNIT-II

1(a) Give classification of transducer with example.

(b) What is working principle of piezoelectric transducers?

2(a) Explain the characteristics & applications of thermistors.

(b) How is the displacement measured using LVDT.

3. A strain gauges bounded to a steel beam of 0.20 meter long & has a cross

sectional area of 0.4*10-3

meter Young’s modulus of elasticity for steel is

200GN/m2 . The strain gauge has a unstrained resistance of 120Ω & a gauge of 2.

When load is applied the gauge resistance changes by 0.012Ω. Calculate the

change in length of steel beam & the amount of force applied to the beam.

4. Differentiate the active & Passive transducers with their applications.

5. Write a short note on transducers used for temperature measurement along with

their performance characteristics.

6. Explain the procedure for measurement of liquid level with the help of

capacitive transducer.

7. A Pressure measuring instrument uses a capacitive transducer having a spacing

of 4mm between its diaphragms. A pressure of 600KN/m2 produces an average

deflection of 0.3mm of the diaphragms of the transducer. The transducer which has

a capacitance of 300PF. Before application of pressure & is connected in &

oscillator ckt. having a frequency of 100KHz. Determine the change in frequency

of the oscillator after the pressure is applied to transducer.

UNIT-III

1. Draw the Block diagram of digital data acquisition system & explain each

block.

2. Explain the concept of open loop & closed loop control systems by giving

suitable examples & also highlights their merits & demerits.

3(a) Determine the overall transfer function (C/R) of the system shown in fig. by

block diagram reduction technique.

(b) Draw the signal flow graph of the above system & verify the result by using

mason’s gain formula.

4. Determine the C(S)/R(S) for the system whose block diagram is given in

fig.

5. Derive an expression for the transfer function of two phase servomotor.

Also state the assumptions to make the transfer function approach to be valid

for two phase servomotor.

6. Use Mason’s gain formula to find the transfer function C(S)/R(S) for the

signal flow graph shown below-

UNIT-IV

1. Determine the transfer function relating x1(s) to F(S) for the mechanical

system shown in fig.-

2. Determine the mathematical model equations for a mechanical system as

shown in figure-

3. Find the dynamic error coefficients of the unity feedback system whose

forward transfer function is-

G(S) = 10/s(s+1)

4. A second order control system has a unity feedback & an open loop transfer

function

G(S) = 500/s(s+15)

(a) Draw a block diagram for the closed loop system.

(b) Write down the characteristic equation of the closed loop.

(c) What are the numerical values of natural frequency (wn) & damping

ratio (δ).

(d) Find the values of % maximum overshoot (Mp) & the time from start of

the transient to max. overshoot (tp).

(e) What is setting time (ts) of the system.

(f) If the system is subjected to a ramp input of 0.5rad/sec. What is the

steady state error (e ss).

5. The open loop transfer function of unity feedback control system is given

by-

G(S) = KA Ke Km / s(1+sT)

Where Ke=20, KA=5

Further, the system response to unity step input is given by-

C(t) = 1-1.25e-10t

+0.25e-50t

(a) Closed loop transfer function

(b) Determine T , Km.

(c) Damping ratio

(d) Velocity error to unit ramp input.

6. Discuss the advantages & disadvantage of feedback with special reference

to

(a) Gain

(b) Reduction of parameter variation

(c) Control over system dynamics

(d) Control of the effects of disturbance signals.

UNIT-V

1. With the help of Routh Hurwitz criterion comments upon the stability of the

system having the following characteristic equation

S6+s

5-2s

4-3s

3-7s

2-4s-4=0

2(a) The closed loop transfer function of an antenna control system is given by-

T(s) = k/(s4+6s

3+30s

2+60s+k)

Determine the range in which k must lie for the system to be stable.

(b) How many roots does each of the following polynomials have in the

right half of the s-plane.

(i) s4+2s

3+4s

2+8s+15

(ii) s6+4s

5+11s

4+12s

3+26s

2+84s+16

3. The open loop transfer function of a unity feedback control system is-

G(s) = k/s(s2+4s+8)

Sketch the root loci of the system, touching the following points

(a) Number of the root loci

(b) Number of asymptotes

(c) Angle of asymptotes & their real-axis intercept

(d) Angle of departure

(e) Imaginary axis intercepts

(f) Real axis part of root locus.

4. The open loop transfer function of a unity gain feedback is given by-

G(s) = k(s+2)/(s4+3s

3+4s

2+2s) , k>=0

(a) Determine all the poles & zeros of G(s).

(b) Draw the root locus.

5. Investigate the stability of a closed loop system with the following open loop

transfer function using Nyquist stability criterion-

G(s) H(s) = k(s+3)/s(s-1)

6. Sketch the polar plot for the following transfer function-

G(s) = 1/s(s+1)

7. Sketch the bode plot for a unity feedback system characterized by the open

loop transfer function-

G(s) = 1000/ (1+0.1s)(1+0.001s)

Find-

(a) Gain Margin

(b) Phase Margin

(c) Stability of the system

8. Draw the Bode Plot for the transfer function-

G(s) = 50/s(1+0.25s)(1+0.1s)

From the plot determine Gain Margin & Phase Margin.

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